The present invention relates to the warming of physiologic fluids for infusion, such as is done in the treatment of humans or other animals for hypovolemic shock by infusion of physiologic solutions into the body. The invention more particularly relates to a infusion administration device which is capable of warming the physiologic solution to about a normothermic temperature for infusion. Also part of the present invention is a method of bringing a physiologic fluid to within and/or maintaining such a fluid within a normothermic temperature range for its administration into a human or other animal.
Treatment of shock (e.g. hypovolemic shock) can require volumetric fluid replacement and maintenance of a normothermic temperature in vital organs of an animal (e.g. human) body. In order to resuscitate a victim of shock, secondary to traumatic hemorrhage for example, physiologic solutions including blood products, synthetic colloids, and crystalloids, must be infused into the body. These physiologic solutions presently are introduced through a multitude of venipunctures cannulated with 18-gauge or larger internal diameter catheters. The infused physiologic solutions also should be warmed to about a normothermic temperature in order to maintain normothermic temperature in the vital organs of the body and prevent transfusion-induced hypothermia.
In clinical settings, present methods of fluid administration achieve rapid infusion rates when required, and achieve careful heating of the infusion fluid to a normothermic temperature. Various types of such apparatus are disclosed in U.S. Pat. Nos. 3,023,750, 4,177,816, 4,379,453, 4,531,941, 4,623,333, 4,678,460, 4,705,505, 4,735,609, 4,934,336, which are hereby incorporated by reference.
The need for warming of the infused products can be seen, for instance, in the administration of cold fluids such as banked blood which is often stored in a refrigerated environment at a temperature of about 4.degree. C. Patients who receive as little as two units of such cold banked blood tend to become hypothermic. The first major organ to be exposed to the stream of cold bank blood is the heart. Heart rate, blood pressure, cardiac output, and coronary blood flow all fall progressively as body temperature drops; thus, the need exists for warming of the infused products prior to their infusion.
In non-clinical settings, the physiologic solutions are subjected to even more severe conditions. Such non-clinical settings include emergency vehicles and ambulances in the field, medical helicopters in the field, and the like. Depending upon the climate, the physiologic solutions may be subjected to cold temperatures due to the environment. Also, conventional methods for warming of the physiologic solutions cannot readily be implemented away from the emergency vehicle as a power supply is not readily available. Moreover, for blood products, a maximum temperature of 42.degree. C. must not be exceeded; otherwise, the blood cells can hemolyze with resultant disqualification of such blood products for their infusion. Moreover, non-blood products normally will be stored at ambient temperature as refrigeration is not required for preservation purposes. However, there is still a need in non-clinical settings to adjust and/or maintain the temperature of physiologic fluids prior to their infusion into the body.
Other applications for the present invention include the administration of blood, blood products, or any of several non-blood materials or products in clinical or emergency settings, beyond those described above.